A persistent difficulty and hotspot in the field of photovoltaics is to prepare low-cost, high-energy solar cells using cheap materials. Currently, the application of crystalline silicon cell used for the ground is greatly confined because of its complicated process and high cost. In order to reduce the cost of the battery, it has been a long time for people to seek for a new solar cell material to cut the cost and expand the application. Organic semiconductor material has attracted considerable attention owing to its advantages of available raw material, low cost, simple process, good environmental stability and good photovoltaic effect. Since photo-induced electron transfer phenomenon between conjugated polymer and C60 was reported on Science (N. S Sariciftci, L. S milowitz, A. J. Heeger, et al. Science, 1992, 258, 1474) by N. S. Sariciftci, et al. in 1992, considerable efforts have been directed toward developing polymer solar cells, and a rapid development is achieved. However, the conversion efficiency is much lower than that of inorganic solar cells. What mainly constrain performance improvements are: mismatch between spectral response of organic semiconductor material and solar spectrum, relatively lower carrier mobility of organic semiconductor, relatively lower efficiency of electron collecting of carrier, etc. To put polymer solar cell into practice, a primary task in such field is to develop new material and to substantially promote its energy conversion efficiency.
Porphyrin is the collective name for types of macrocyclic compounds of substituted porphins, porphin consisting of four pyrrole rings joined together by four methine groups is delocalized π-electrons conjugated system of a flat macrocycle structure having alternating single and double bonds. They have good quantum efficiency in charge-transfer and energy-transfer reaction, great electronic buffer properties, photoelectric magnetic properties, stiffness, as well as excellent thermal stability and environmental stability. Thus, porphyrins organic semiconductor materials are a kind of promising materials, of which the application in the field of photovoltaic is widely investigated. Almost all of the elements and some nonmetals in the Periodic Table can react with porphyrins to form coordination complex. These compounds include most of the metals in main groups and subgroups, some lanthanide metals (Pr, Eu, and Yb etc.) have been synthesized. Porphyrins are macro conjugated system with 18 of π-electrons, so the mobility of electrons migrating within the ring is pretty good, as a consequence, most metalloporphyrin have good photoelectric properties.
However, metalloporphyrin-benzene organic semiconductor material containing silafluorenyl has not been reported on any literature and patent, which greatly refined the application of organic semiconductor material. Thus, the present invention developed a kind of silafluorenyl metalloporphyrin-benzene organic semiconductor material. By the introduction of silafluorene group into parent porphyrin, coordination of metal ions, adjustment of band gaps of porphyrin copolymer, the present invention gains better stability, film forming property, and broadens the absorption range of visible spectrum to near-infrared region, and improves the use of sunlight, at the same time, carrier mobility is improved, the application in the field of organic solar cells and others is broadened.